The U.S. Census Bureau has recently published a working paper on the counting of the gay community in the census. It was done in reaction to articles about how the gay community is not being counted. You can find the working paper at:

Since 2000, Census Bureau editing programs have assigned the response of the person reported as the spouse of the householder in a same-sex couple household to that of being the unmarried partner of the householder. Up until 2004, no state granted marriage licenses to same-sex couples in the United States. However, marriages between same-sex couples have been legal in Massachusetts since 2004, in Connecticut since 2008, and briefly in California in 2008, thus creating differences in how respondents report data and how data are shown in Census Bureau publications. We will discuss the history of these editing decisions and present “unofficial” estimates of the numbers of respondents who reported themselves as same-sex married couples in Census 2000 and in the American Community Survey during the transitional periods when states began to legalize same-sex marriages. Finally, we will present some general characteristics of opposite-sex couples, both married and unmarried, and of same-sex unmarried couples, by their reporting status.

An excerpt from the introduction:

An additional consideration at this time involved the passage of the 1996 Defense of Marriage Act (DOMA). While the Census Bureau counts everyone regardless of his or her sexual orientation or marital status, as a federal agency it also follows the guidelines specified in DOMA. This act provides the definition of marriage and spouse for purposes of federal law:

"In determining the meaning of any Act of Congress, or of any ruling, regulation, or interpretation of the various administrative bureaus and agencies of the United States, the word 'marriage' means only a legal union between one man and one woman as husband and wife, and the word 'spouse' refers only to a person of the opposite sex who is a husband or a wife."

This definition does not include marriages between people of the same sex, even if they have been married under the laws of individual states. Inasmuch as the Census Bureau is a federal agency and provides data to other federal agencies for the purposes of enacting their programs that follow the same federal guidelines, the Census Bureau’s editing and tabulation practices are consistent with the guidelines in this federal law.

Until 2004, no state granted marriage licenses to same-sex couples in the United States. Thus, there was no difference between state and federal law, and during this period the Bureau’s procedure was generally not in dispute. However, marriages between same-sex couples have been legal under state laws beginning in May 2004 in Massachusetts and from June to November 2008 in California, thus creating possible differences in how data are reported by respondents in surveys and how data are shown and tabulated in official Census Bureau reports. In October 2008, the state supreme court in Connecticut also ruled that excluding same-sex marriages was unconstitutional, thus adding a third state which allowed same-sex marriages at some time during calendar year 2008.

In the November 2008 election, voters in California amended that state’s constitution by banning same-sex marriages, thus overturning a state court ruling in June that previously approved same-sex marriages. As of the writing of this paper in early 2009, Massachusetts, Connecticut and Iowa, and most recently Vermont allow same-sex marriages to be performed in those states.

There is no certainty how this issue will resolve itself among the remaining states or whether any changes will be made to any provisions of the 1996 Defense of Marriage Act.